The present invention is directed generally to a drawn implement equipped with an internal steering cylinder and steering arm for corrective steering of the implement when the towing vehicle becomes offset relative to a ground row because of driver fatigue or any other reason.
It has long been a problem in the operation of farm equipment to guide implements through a crop field without accidentally deviating from the crop rows and destroying planted crops. Some agricultural implements carry ground working tools spaced as close as four inches (4") apart. The tractor operator is generally situated in a cab located several feet above and forwardly of the implement where it may be difficult to view the actual engagement of the tools with the ground. Thus the operator must simply attempt to keep the tractor centered relative to the crop rows.
The problem of maintaining the ground working tools between the crop rows becomes critical in an operation, such as cultivating, where a slight lateral misalignment of the tractor relative to the crop rows will cause the implement to uproot several rows of crops. The problem is compounded by the great width of modern cultivators capable of working as many as sixteen (16) or more rows. Furthermore, as the operator spends many hours in the field, fatigue makes it increasingly difficult to constantly maintain proper steering of the tractor. In the small amount of time it takes to turn from observing the implement to looking forward to align the tractor in the row, several feet of crops in multiple rows can be uprooted.
For three-point hitch mounted implements, a row following guidance device has been disclosed in Schmidt U.S. Pat. No. 4,640,365, which provides a row following wheel or other sensor for detecting transverse movement of the implement relative to a crop row. The sensor is connected to a pair of hydraulic cylinders for pivoting the implement tool bar about an imaginary central vertical axis for corrective steering of the implement to maintain its proper position even when the tractor becomes offset relative to crop rows. Such a guidance device is commercially available from Sunco Marketing of North Platte, Nebr., under the ACURA-TRAK trademark. Because that device effectively accomplishes a shortening and lengthening of the two lower links of a three-point hitch connection to a tractor, it is inapplicable for drawn implements having a tongue adapted for connection to the drawbar of a tractor.
Previous attempts to afford corrective steering for drawn implements have all had certain shortcomings which limit their usefulness. For example, Titzmann, East German Patent No. 55,168, discloses an implement having a hitch arm pivotally connected to the implement with a hydraulic cylinder extending between the implement and a medial position of the hitch arm. The external connection of the hydraulic cylinder to the tool bar of the implement limits the positions along the tool bar at which ground working tools can be mounted, rendering the implement inoperative for certain tool placements. A similar hydraulic cylinder and hitch bar arrangement is disclosed in Beck, U.S. Pat. No. 4,607,716, wherein an auxiliary U-shaped frame extends forwardly of the tool bar for pivotal connection to the hitch arm. Schmidt U.S. Pat. No. 3,326,319, discloses an implement having a special articulated hitch arm with an external cylinder 14 to afford pivotal movement between the parts of the hitch arm. Finally, Collogan, U.S. Pat. No. 4,180,133, discloses another two-part articulated hitch arm requiring a double connection to the drawbar by both the forward portion of the hitch arm and a hydraulic cylinder having its other end connected to a brace on the side of the hitch arm. That cylinder, however, effects pivotal movement of the hitch arm relative to the tractor drawbar, leaving the implement frame freely pivotable relative to the opposite end of the hitch arm.
Perhaps the most significant use of the present invention will be on drawn agricultural planter implements. For ridge planting in particular, it is critical that the planter units follow the tops of the ridges to assure proper seed placement. To compensate for inevitable driver fatigue, a guidance system is required which can follow the old furrows and effect corrective steering of the planter implement to maintain its proper position even if the tractor varies somewhat from its intended path.
Proper implement placement relative to crop rows is particularly important for contour farming where the crop rows follow the edge of a terrace or extend around a hill. On the first pass along a contour, a cutter wheel makes a furrow that must be precisely followed by the planter on the next pass if uniform spacing between crop rows is to be maintained. Similar guidance is needed for following the furrow of an even row marker.
A primary object of the invention, therefore, is to provide a drawn implement with a guidance system capable of effecting pivotal steering movement of the implement frame relative to the hitch arm without interference with the mounting of tools on the implement frame.
Another object of the invention is to provide such a guidance system wherein the power source for effecting pivotal movement of the hitch arm is substantially concealed within the implement frame.
Another object is to provide such an implement wherein the pivotal connection between the hitch arm and power source is situated rearwardly of the pivotal connection of the implement frame to the hitch arm.
Another object is to provide a drawn implement with a guidance system which is simple and rugged in construction, economical to manufacture and efficient in operation.